nrml
ConcurrencyPro problem

Stop Concurrent Edits Overwriting Each Other

Enforce the version check a collaborative writer skips, so a stale edit loses instead of winning.

The scenario

Enforce the version check a collaborative writer skips, so a stale edit loses instead of winning.

A failure to reason about

Two editors start from the same revision and the second save silently overwrites the first editor’s changes.

Illustrative context for the topic. The exercise’s full requirements arrive in the workspace.

Questions to bring to your review

  • Which caller makes the reported behavior visible?
  • What focused regression would distinguish the current behavior from the requirement?
  • What existing behavior must remain intact after the change?

Skills you will practice

  • Optimistic concurrency
  • Conflict detection
  • State machines

Read the existing code, reproduce the reported behavior, review proposed changes, and verify your final implementation. You can use AI assistance while staying responsible for the result.

Prepare with a worked example

See how nrml evaluates an attempt, including the limits of automated evidence.